Microstructural dependence of magnetic properties of Pt/Co multilayer thin films

Abstract

The magnetic properties of thin film Pt/Co multilayers with perpendicular magnetic anisotropy depend on their preparation. Vapor-deposited and Xe-sputtered multilayers have the largest anisotropy energy and coercivities, attractive for magneto-optical recording media. Films sputtered with a smaller mass gas (Ar) have less attractive magnetic properties. In this paper it is shown by high resolution electron microscopy that microstructural differences, related to the energetics of the deposition process, caused the differences in magnetic properties. Films prepared by Ar-sputtering experienced energetic bombardment by reflected Ar neutrals and consequently had smooth, continuous Co and Pt layers, but only modest (111) fcc texture. Vapor-deposited and Xe-sputtered films, which experienced much less energetic bombardment, had superior (111) texture and sharp column boundaries, although Co-Pt layer interfaces were rougher. It was concluded that the superior (111) fcc texture was responsible for a large magnetic anisotropy energy. And both the larger anisotropy energy and the sharper column boundaries contributed to large coercivities.